| Summary: | 碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程研究所 === 100 === The world produces 2.64 hundred-million metric tons of soybean and generates 40 million metric tons of soy waste. Soy waste contains 15-30% of non-edible oils that can be extracted and converted into biodiesels. Residual oils containing high concentrations of free fatty acids have to be pre-esterified when the conventional alkali trans-esterification method is used. To reduce processing steps, an enzymatic method that directly converts oils with high concentrations of free acids is desired.
This work was to study the feasibility of converting soy residue oils from soy curds, soy sauce and spent bleaching earth into biodiesels by enzymatic methods using Candida rugosa Type VII, Novozym 435 and compound-lipase (Novozym 435&Lipozyme TL IM) as enzyme.
Experimental results showed that the yields were from 84.7% to 92.7%, and Novozym 435 was the enzyme that gave a highest conversion of 92.7% among all enzymes, which was slightly higher than the alkali method by previous researchers.
The enzymatic method has several advantages such as less processing step higher product yield, tolerance of low quality feedstock, and significantly less wastewater generation, but the prices of enzymes account for 80-90% of the production cost. To be economic feasible, inexpensive enzymes have to be developed and used. Therefore, future work will focus on finding cheaper lipase as the catalyst.
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